Jedime's Po' Boy Star Wars Customs

Rebel Briefing R2 Unit

Well, technically this R2 exists in the Star Wars universe, or at least it did. It can be seen in an unused shot from the briefing scene. If R2-X2 is any indication, they probably used him in the back of an X-Wing (the Y-Wing pilots didn't actually have any astromechs behind them), but most are pretty hard to see.